Basic Physics Questions and Answers

A projectile of mass m is thrown from the origin O with a speed v0 at an angle e Identify the CORRECT statement Y4 C 0 Angular momentum of the particle about O is always zero Angular momentum of the particle about O increases with time A constant torque acts on the particle about O in the clockwise sense

c only i d i and ii are correct and iii is wrong 38 A molecule of a substance has a permanent electric dipole moment of magnitude 10 cm A mole of this substance is polarised by applying a strong electrostatic field of magnitude 10 V m The direction of field is changed by an angle 60 The heat released by the substance in aligning its dipole along the new direction of the field is a 6 b 31 c 3J alectric dipole of length d 6J 20 cm having ith respect to

ye fe O 2 Two identical metallic spheres each of radius r are fixed with their centres at points d 0 0 and d 0 0 in a homogeneous medium of conductivity o Here d r One of them is maintained at potential V and the other one is grounded as shown in the figure Calculate magnetic flux density at a point that is in the y z plane at a distance R from the origin O Ans Moord d d I Bate R loc disk can rotate about its central vertical axis in a A largo friotic

A ring of mean radius r and cross sectional area A is made of a perfectly conducting wire Inductance L of the ring is so small that inertia of free electrons cannot be neglected in the current building process The free electron density in the conductor is n mass of an electron is m and modulus of charge on an electron is e Initially the ring is placed in a uniform magnetic field with its plane parallel to induction vector B of the field as shown in the figure Find the current in the ring after it is A turned through an angle 90 18 B 4 2xrm 2 O B

50 A spherical capacitor consists of two concentric spherical conductors held in position by suitable insulating supports as shown in figure The capacitance C of this spherical capacitor is 4RE a c 47E12 71 72 1 2 b d 7 1

8 The P V diagram of a gas undergoing a cyclic process ABCDA is show in graph where P is in N m and V is in Cm Identify the incorre statement a b c d N m P 2 10 10 A D 2 0 B C 4 0 V cm 0 4 J of work is done by the gas from A to B 0 2 J of work is done on the gas from C to D No work is done by the gas from B to C Work is done by the gas in going from B to C and on the gas fro

One mole of an ideal gas at temperature T expands slowly according to the law P constant It final V temperature is T2 The work done by the gas is Question Type Single Correct Type 1 R T T 2 2R T2 T 3 R 2 T T 2R IT

A train with cross sectional area St is moving with speed vt inside a long Vt tunnel of cross sectional area So So 4St Assume that almost all the air density rho in front of the train flows back between its sides and the walls of the tunnel Also the air flow with respect to the train is steady and laminar Take the ambient pressure and that inside the train to be po If the pressure in the region between the sides of the train and the tunnel walls is p then po p Share Answer Apply continuity equation at R and S 4st X Vt V x 3St V Vt P V i V Apply Bernoulli equation at R and S V 2 7 2N 2 Po P pvz The value of Nis Vt2 2 2 Po P V V ii Open in answr app

released by the new direction of the field is a 61 b 3 c 3J d 6 J An electric dipole of length 20 cm having 3 x 10 C charge placed at 60 with respect to a uniform electric field experiences a torque of magnitude 6 Nm The potential energy of the dipole is a 2 3 J c 3 2 J b 5 3 J d 3 5 J

b The wheel shown in the diagram has an axle passing through its centre O The wheel is kept stationary under the action of i A horizontal force F1 at A ii A vertical force F2 at B Show the direction of F1 and F2 in the diagram B 3

A block with charge q placed on a smooth horizontal surface and connected to two springs is in equilibrium Springs are massless and relaxed Now a horizontal electric field E is switched on in the region Maximum compression or extension in the springs is 3K www q 6K www Smooth horizontal surface

c In the region of stre surfaces are far apart d Both the statements a and b are correct 27 What is the angle between electric field and equipotential surface a 90 always c 0 to 90 b 0 always d 0 to 180 a b c d 33 A s wit 5

Q57 Work done in raising a box on a platform depends on which of the following Ops A The strength of the man O How fast it is raised C O To the height which it is raised B D None of the mentioned options 100

Two point charges 1 C and 1 C are placed at respectively in points 0 0 1m and 0 0 1m XY plane Then choose the correct statement s from the following A B C D The electric field at all points on the Y axis has the same direction The dipole moment is 0 2 C m along X direction No work has to be done in bringing a test charge from infinity to the origin Electric field at all points on the X axis is along Y axis

35 In a semiconductor diode the reverse biased current is due to drift of free electrons and holes caused by 1 Thermal excitations only 2 Impurity atoms only 3 Both 1 2 4 Neither 1 nor 2

D The thermodynamic state of an ideal gas varied through different processes as shown in the figure The change in internal energy of the process A B and C respectively will be Pressure P 1 2 0 3 0 adiabatic Isothermal Isobaric Volume V

52 When measuring the radius of a sphere an error of 0 6 takes place in the measurement What will be the permissible error while measuring the surface area s A O 0 06 B C O 0 012 1 2 D O 0 12

C 3 20 J A shooter fires a bullet of mass 50 g with speed of 200 m s on soft wood of thickness 2 cm If bullet looses 80 of its kinetic energy and emerges out What is emergent NCERT Pg 118 bullet speed 1 89 4 m s 1 2 69 5 m s 1 3 100 m s 1 4 20 0 m s 1 A woman pushes a box on railway platform inplies a force

A deer is running at constant speed It watches a lion and increases its speed by 5 m s per each second If after watching the lion it travels 400 m in 10 s find its velocity before it watches the lion 1 25m s 2 10m s 3 65m s 4 15m s

In an undisturbed airstream where the pressure and density is at standard atmosphere and the velocity is 600 m s What are the velocity pressure temperature and speed of sound where the density is 0 411 kg m 3 Choices are 752 m s 760 12 m s 186 07 K 21 964 Pa 21 963 66 Pa 274 m s 273 50 m s 185 23 K 186 K 751 61 m s 275 18 m s 22 000 Pa

Show that the form under the integral sign is exact in the plane or space and evaluate the integral Hint Show that curlF 0 and find the scalar potential function f of F F dr f B A 1 1 0 00 ex y z xdx ydy zdz 0 0 0

mich of the following best describes nonvolatile memory TIONS nonmagnetic memory magnetic memory memory that loses stored information when electrical power is remo

5 cm thick walls of a box like cooler is made of plastic foam Its total surface area is 1 5 m If outside temperature is 30 C then how much ice melts each hours inside the cooler to hold its temperature at 0 C Given L for plastic 0 04 W mK Lo 1 kcal 4 184 kJ kcal 80 cal g and

Use the figure to answer each of the following 1 Name the right triangle of AABC 2 What is the altitude to the hypotenuse of AABC 3 Name the hypotenuse of AABC 4 Two segments of the hypotenuse Are AD and 5 The hypotenuse of ABCD if CD LAB is 6 Name the right angle of AACD 7 Name the hypotenuse of right ABCD 8 AADC 9 AABC A 10 AABC D Th fo

4 1920 The measured length of two rods are 30 cm 0 5 cm and 2 20 cm 0 1 cm The percentage error in difference of length of NCERT Pg 26 rods is 1 6 2 4 3 5

Paragraph for Questions 19 and 20 A car starts from rest and accelerates as shown in the accompanying diagram 4 2 Acceleration in m s 4 2 4 6 8 Time in seconds At what time would the car be moving with the greatest velocity A 2 seconds B 4 seconds C 6 seconds At what time would the car be farthest from its original starting position A 2 seconds B 4 seconds C 6 seconds D 8 seconds D 8 seconds

A man of mass m on an initially stationary boat gets off the boat by leaping to the left in an exactl horizontal direction Immmediately after the leap the boat of mass M is observed to be moving to the right with speed v Mark the incorrect statement Neglect friction offered by water on boat O Work done by man on boat is m v Total work done by man is M m Mv Velocity of centre of mass of system is zero Work done by man on himself M V

1 160 8 W 2 259 2 W 3 302 5 W 4 239 2 W An electron and a proton are detected in cosmic ray experiment The electron has kinetic energy of 20 keV and proton has 50 Work Energ keV The ratio of speed of electron to proton is me 9 x 10 31 kg mp 1 6 10 27 kg INCERT Pg 136 1 15 7 3 26 6 2 17 5 4 4 9

influence of gravity travels from the higher to the lower point in least time b Obtain the generating function for the transformation p 1 Q and q PQ

A point moves with uniform acceleration and v v and v denote the average velocities in the three successive intervals of time t t and t Which of the following relations is correct 1 V V V V3 t t t t3 2 V V V V3 t t t 13 3 V V V V3 t t t t3 4 V V V V3 t t 1 13

A hollow non conducting sphere A and a solid non conducting sphere B of equal radius R and masses m and 2m are kept at a large distance apart on a rough horizontal surface Charge on the two spheres A and B are Q and 2Q respectively Charges are distributed uniformly and remain constant and uniform as the spheres come closer Friction is sufficient to support pure rolling and the kinetic energy of the two spheres just before collision is KA and KB Find 100 KA KB Q A m R 2Q O B 2m TR

In an interference pattern the position of central maxima is 5 mm from a certain point P on the screen The fringe width is 0 6 mm The distance of the third minima from point P is 1 3 2 mm 2 3 3 mm 3 3 5 mm 4 3 8 mm

A thin uniform elastic rod of natural length L density p and Young s modulus Y is just completely immersed in vertical position in fluid of density 2p by applying a vertically downward force at its top end The rod is in equilibrium then pick up the correct option g is acceleration due to gravity downward force 1 There is net compression in rod of magnitude 2 There is net compression in rod of magnitude 3 There is net compression in rod of magnitude 4 There is net compression in rod of magnitude plag 4Y 3pL g 2Y pL g 2Y PL g Y

1 2 3 Higher speeds compared to all other types of A D convertors Very good accuracy without putting extreme requirements on component stability Good rejection of power supply hum

hemispherical earth plate is buried into the earth Find the Otential difference between the feet of a man standing on round as shown in figure Current through earth plate is I onductivity of earth is 10 I 14 up to two decimal places IV 2m 1m

as 1 14 The distance between H and CI ions in HCl molecules is 1 38 A The potential due to this dipole at a distance of 10 A on the axis of dipole is a 2 1 V b 1 8 V d 1 2 V c 0 2 V inte a h c and d are set at

A parallel beam of light is incident on a tube containing two convex lenses of focal length 5cm and 10 cm as shown the rays are incident on the 5 cm focal length lens first If the diameter of incident beam is 1 6cm then the diameter of final beam is A 4 cm B 2 31 cm C 3 2 cm D 6 cm

Gravitational potential difference between a point on surface of planet and another point 10 m above is 4 J kg Considering gravitational field to be uniform how much work is done in moving a mass of 2 kg from the surface to a point 5 m above the surface O4J O 5 J 06 J 7J

1 A cube of side x has a charge dat each of its vertices The potential due to this charge array at the centre of the cube is a c 49 3KE X 3q 4q 3TEX 29 d TE b

AIMS 92 Which of the following has the highest moment of inertia when each of them has the same mass and the same radius a A hollow sphere about one of its diameters b A solid sphere about one of its diameters c A disc about its central axis perpendicular to the plane of the disc d A ring about its central axis perpendicular to the BHU

Imagine a helicopter hovering at a small height above a man standing on the ground Helicopter rotor has two identical blades Man is looking directly towards helicopter We refer to the actual direction of rotation of blades as true direction Assume human eyes takes fifteen pictures or frame per second A If rotor is rotating at 90 rad s blades will appear to him rotating in true direction B If rotor is rotating at 90 rad s blades will appear to him rotating opposite to true direction C If rotor is rotating at 195 rad s blades will appear to him rotating in true direction D If rotor is rotating at 195 rad s blades will appear to him rotating opposite to true direction

A straight wire of length L and mass M carries a current I It is placed on a horizontal rough surface and a vertical magnetic field B is switched on The coefficient of friction between the wire and the surface is u Find the least value of B which can make the wire translate Give your answer for L 1 0m M 50 g I 5A and 0 5 How will your answer change if direction of B is reversed

A man of mass m is standing on a platform of mass m kept on a smooth horizontal surface If the man starts moving on the platform with a velocity v relative to the platform then recoil velocity of platform is Question Type Single Correct Type 1 2 3 m v m m m v m m m m v m m m v

14 cm 7 An insect starts moving up in a liquid from point O of variable refractive index o 1 ay where y is depth of liquid from the surface If u is the speed of insect its apparent speed to the observer E is a u ln 1 aH u b 1 aH po c u In 1 aH d none E H

13 Select correct statement related to heat 1 Heat is possessed by a body 2 Hot water contains more heat as compared to cold water 3 Heat is a energy which flows due to temperature differen 4 All of these

3 A is a vector of magnitude 2 7 units due east What is the magnitude and direction of vector 4A 1 4 units due east 2 4 units due west 3 2 7 units due east 4 10 8 units due east

A vertical clean glass tube of uniform bore is to be used as a piezometer for measuring pressure of a liquid at a point The liquid has a mass density of 1425 kg m and a surface tension of 0 06 N m in contact with air If the capillary rise in the tube is not to exceed 2 0 mm the required minimum diameter of the tube is mm Take angle of contact with glass is zero

In an H like atom when electron transits from energy state n 5 to n 2 a photon of wavelength 134 nm is emitted What will be the wavelength of photon emitted when the transition occurs from energy state n 4 to n 2 1 486 nm Upi 2 450 nm

7 Force of gravitation between two masses is found to be F in vacuum If both the masses are dipped in water at same distance then new force will be 1 F 2 F 3 F 4 Cannot say

10 Soap helps in cleaning clothes because 1 It attracts the dirt particles 2 It decreases the surface tension of water 3 It increases the cohesive force between water molecules 4 It increases the angle of contact